In the field of latest stretch-wrapping of foods, such as vegetables and fruits, fishes, meats, and cooked foods, either as they are or placed on a plastic tray, i.e., so-called prewrapping with plastic films, use of ethylene resins such as low-density polyethylene resins and ethylene-vinyl acetate copolymer resins, have been studied with keenness as substitutes for conventionally employed polyvinyl chloride films from safety and hygiene considerations.
However, films of known low-density polyethylene resins, e.g., low-density polyethylene and an ethylene-butene-1 copolymer, are hard and difficult to apply to stretch-wrapping. Forced stretching of these films only results in breakage or non-uniform stretching of the film or causes deformation or breakage of the tray with a food on to wrinkle the film, failing to obtain necessary tension or to achieve commercially valuable wrapping.
Films of an ethylene-vinyl acetate copolymer resin, with its vinyl acetate content, melt flow rate, etc. being properly selected, would be freed from the above-described problems associated with low-density polyethylene resin films. However, when they are used in stretch-wrapping of sharp-edged foods or trays, they are torn at the sharp edge. Moreover, any small initial tear of the film which may be made during distribution of wrapped articles runs or spreads into a big tear, eventually leading to unwrapping.
A laminate film composed of the above-mentioned low-density polyethylene resin film and ethylene-vinyl acetate copolymer resin film settles the problems of hardness and non-stretchability but still leaves the problems of easy tearing during wrapping or distribution, particularly with a reduced film thickness.
In order to overcome these disadvantages associated with the conventional stretch-wrapping films, a laminate film composed of an intermediate layer mainly comprising a specific butene-1 polymer resin having laminated on both sides thereof a layer mainly comprising an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of from 5 to 25% by weight which is obtained by blown-film extrusion at a blow-up ratio of from 3 to 7 has been proposed aiming to provide a thin stretch-packing film which is excellent in stretchability, softness and particularly tear strength as well as moderate slip, self-adhesion, sufficient heat-sealability, and transparency, as disclosed in JP-A-61-89040 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Nevertheless, even the above-described stretch-wrapping film does not always satisfy market demands for wrapping with tension fit to the shape of articles to be wrapped without leaving wrinkles and for deformation recovery properties, such as recovery from deformation under load during delivery or display without leaving wrinkles.
Further, U.S. Pat. No. 4,713,282 (corresponding to JP-A-61-4463) discloses a laminate film for stretch-wrapping composed of a layer mainly comprising a propylene-.alpha.-olefin random copolymer resin having laminated on both sides thereof a layer mainly comprising an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of from 5 to 25% by weight. The proposed film is still unsatisfactory to meet the market demand for deformation recovery properties.